Telephone system



Oct. 14, 1941. E. AUCH 2,258,853

TELEPHONE SYSTEM FiledJuly 3l, 1959 3 Sheets-Sheet l` Oc-t. 14, 1941. E. JAUcH 2,258,853

TELEPHONE SYSTEM Filed July 3l, 1939 3 Sheets-Sheet 2 06E/v MUCH l y A Tro/e/VEK oct. 14, 1941. E, MUCH 2,258,853

TELEPHONE lSYSTEM Filed July 3l, 1959 3 Sheets-Sheet 5 l Arrow/Ey.

Patented Oct. 14, 1941 TELEPHONE SYSTEM Eugen Jauch, Berlin-Siemensstadt, Germany, as-

signor to Fides Gesellschaft fr die Verwaltung und Verwertung von gewerblichen Schutzrechten mit'beschrnkter Haftung, Berlin, Germany, a corporation of Germany Application July 31, 1939, Serial No. 287,511

' In Germany August 8, 1938 9 Claims.

The present invention relates to telephone installations with main and sub-exchanges in which the sub-exchanges not provided with local battery feed are connected with the main exchange over a number of two-conductor junctions. The object of the invention is to connect ar calling sub-exchange subscriber to the main exchange over one of the free junctions.

In systems where a sub-exchange is connected to the main exchange over two junctions it is known to connect the calling subscriber of such a sub-exchange by means of start relaysv associated with the subscribers for the individual junctions. Since in known arrangements the sub-exchange is provided with local battery feed these start relays are operated in a local circuit when a subscriber makes a call.

The present invention relates to a method of solving the problem of connecting sub-exchanges not provided with battery feed over a number of two-conductor junctions and of connecting a calling sub-exchange subscriber to a free junction line.' This result is obtained in that, in the sub-exchange, switching arrangements are associated with each subscriber which, on a call from a subscribenare so controlled from the main exchange over one of the junction lines, corresponding to the junction to be used for setting up the connection,v that thecallingsubscriber has access only to the main exchange over this junction.

The invention is illustrated with respect to an embodiment shown in Figs. 1 and 2, Fig. 2 being a continuation of the system to the right of Fig. 1 in which a telephone installation including a subexchange UA without local battery feed is con-A nected to a main exchange HA over two lines (VLI, VLII) Fig. 3 is a modification of the arrangement shown in Fig. 1.

For connecting a, sub-exchange .subscriber to the junction extending to the main exchange a selector is provided at each junction in the subexchange which selector is set by impulses transmitted from the main exchange and each subscriber is also associated with a relay for each indicate thatk the calling sub-exchange Sub- 55 scribers line is engaged and, moreover, for outgoing connections it'switches in the calling subscribers meter at the main exchange.V

For testing the condition of the subscribers line at Kthe. main exchange, testing arrangements are associated with each junction and are connected to the Wipers ofthe previously mentioned switch in which both contacts corresponding to the individual sub-exchange subscribers in the contact banks of the switches for both lines are connectedY together. When indicationfis `given that a subscribers line is engaged at the switch of one junction line the testing apparatus at the switch of the other junction line is seized when the same subscriber has been selected.

In theembodiment the setting-upL of the connections of the telephone system takes place in the manner following:

In the normal condition of the system a 'permanent current circuit is completed over each junction and prepares call circuits over each junction for all the subscribers of the sub-exchange UA. The permanent current circuit over they junction line VLI extends over: earth, battery, winding I of relay XI, contacts 43.1:I, 42g,

e Ma, 34k, wiper mwI in-zero position, a-conductor of the-junctionv line VLI, contact I3 dwl or contact Il lul and wiper wII in zero position, wiper wl2 in zero position,v contactv I-ImI2, relays 4MI I, MIZ, earth. In this circuit relays MII and MI2 areenergised so that its contacts are in the position shown. `Therefore a multipled call circuit for all subscribers ofthe sub-exchange UA is prepared over` the junction VLI to the main eX- change HA. y i

ylhe permanent current circuit over the junction line VLII extends in a corresponding mancorresponding to the two junctionsV aremade accessible to all subscribers of the sub-exchange UA. In the embodiment the arrangement is such thaton a call from a subscriber when bothjunction lines are free, a call circuit is first completed over the junction line VLI in that theY relay X2 of the junction line VLII for receiving the call impulse is short-circuited over contact |041) ofthe, relayBof the junction line VLI scthat 1t cannot be operated by the call and only the relay Xl can be energised. This circuit, when for example the subscriber Tn2 is the calling subscriber, extends over: earth, battery, winding I of relay Xl, contacts, 43ml, 42g, 4ta, 34k, Wiper mwl in zero position, a-conductor of the junction line VLI, contact l3dwl or contact Mul and wiper wl I in zero position, Wiper wl 2 in zero position contacts Sdwl, Smll, resistance Wil, contact lb2, subscriber T112, contacts 84132 and Go2 or 81a2 and 89132, earth. The relay XI by closing contact 59ml locks its winding II over the.

resistance Wil3 in a circuit which after the switch is stepped on extends over wiper mm2, contacts 51:1:I, Slpl, (or, later, 5222) and the resistance WiIZ. Contact 43ml operates when relay Xl is energised and breaks the permanent current circuit extending oper the a-conductor of the junction line VLI so that, in the'sub-exchange UA, the relays MII and Ml2 are disconnected. 'Ihese two relays allow their operated contacts 'Iml2, mll and llmlZ to open, interrupting the multiply-connected call circuit in the sub-exchange and the permanent current circuit while the rotary magnet Dwl of the selector in `thesub-exchange UA is connected to the b-conductorof the junction VLI by the closing of contact I'Iml I and thus the following circuit is completed: earth, battery, Winding I of relay K, contact 60g/,wiper mw i-n zero position, contact 55q,

b-conductor of the junction line VLI, contacts Iul, Il ml I, rotary magnet Dwl, earth.l In this circuit relay K and rotary magnet Dwl are energised. Winding I of relay A is connected to the a-conductor of thejunction line VLI by the closing of contact 35k so that, after the selector in the sub-exchange is stepped-011 by the rotary magnet Dwl energising, over the contact I2dwl Awhich is operated -by the rotary magnet Dwl the following circuit is completed: earth, battery, winding I of relay A, contacts we, 35a., 38g, 33ml 35k, wiper mwl in zero position, a-conductor, of the junction line VLI, contact l2dwl, Wiper wl3 on the segment I-B, resistance Wi5, earth. In this circuit relay A is energised so that contact 48a closes and causes the rotary magnet Dmw of the switch in the main exchange to energise over: earth, battery, rotary magnet Dmw, contacts Mq, -48 z, Elib, dflpl, earth. The switch mechanism in the main exchange is advanced by one step. Relay Y is energised over its winding I by the closing of contact 3 ldmw -so that as contact lilly is opened the winding I of relay K is disconnected. The circuit extending over the b-conductor of the junction VLI for the rotary magnet Dwl is interrupted after the stepping-on of the switch at the main exchange at wiper mwB, so that kthe circuit completed for the winding I of relay A over the JL-conductor of the junction VLI is disconnected by the opening of Contact IZdwL Relay A is thus disconnected .and breaks the circuit of the rotary magnet Dmw at contact 48a so since contactjSldmw is opened the relay Y restores.

, ,During the period during which relay Y is energisedlrelay K is not energised, the test circuit for determining the calling subscriber is prepared in that battery potential `is connected to the acon ductor over the resistance Will .and contact 31g and earth potential is connected tothe b-conduc toroverlthe contact Elk and the test relay B. By means 4of the battery ,potential on the a-conductor `in the sub-exchange relay Al, connected over wiper wII of the subscriber Tnl (not shown), is

,energised in A'order to determine whether this subi scriber is the calling subscriber. If the subscriber (not shown,) is already connected to the junction line VLII then, since his relay Bl is energised, an energisation of relay Al is prevented so that the subscribers conversation over the other junction line is not disturbed.

Since, in the present case, the subscriber T112 makes a call, after the switch is rst stepped-on there is still no test circuit completed and after the energisation of relay Y and the closing of contact Sty, the winding I of relay K, is energised again over: earth, battery, Winding I of relay K, contact Sty, resistance Wi'lll, contacts 541i, 5311, wiper mm2 on segment l-5, earth. The relay K over its contact 257e connects battery to the b-conductor. The interaction described above is repeated so that in the sub-exchange the selector is advanced by a further step and by sending back an impulse over the a-conductor of the junction VLI the relay A in the main exchange is also advanced by a further step. After the second step relay A2 is energised as long as relay Y is energised over: earth, battery, resistance Wil I, contacts 371/, 33ml, wiper mwl on segment l-6, a-conductor of the junction line VLI, contact Mul, wiper wll on contact 2, winding I of relay A2', contact |5122, earth. The relay A2 disconnects the calling subscriber T112 from the junction VLII. Moreover, the calling subscriber is connected over contact 3a2 with a branch, used for all subscribers, multipled to the a-conductor at which branch a condenser is connected for bridging over the A-relay, while at contact 86a2 a corresponding connection is effective for bridging over the relay Ul at the b-conductor. In `this special arrangement two condensers only are used for bridging over the relays at cach conductor for all the subscribers.

After these operations, taking place over the subscribers loop the following circuit is completed: earth, battery, resistance Will, contacts 311/, 33ml, wiper mwl on segment l-6, a-conductor of the junction line VLI, contact I Sdwl, Wiper wl2, on the contact 2, winding II of relay A2, contact lb2, subscriber T112, contact 84b2, 5a2, relay Ul, contact lul, earth. In this circuit relay A2 remains energised while relay UI is energsed so that, with disconnection of earth at contact l9ul and of the rotary magnet Dwl at contact lul, the b-conductor of the junction line VLI between the calling subscribe;` T112 and the main exchange HA is switched through over the contact 2ilul. Over the calling subscribers loop the relay B, connected to the b-conductor of the junction line VLI, is now energised in series with relays Ulr and A2 since contact Elk is closed. By

the opening of contact 5to a further energisation of the rotary magnet Dmw is prevented. Relay Y now restores and in place of the resistance Wil l connects the relay A to the a-conductor so that now this relay is energised in series with the relays A2, UI and B.

Meanwhile, by the closing of contact 59D, the

relay RI is energised over the choke Dl for the .becalledover the junction line VLII according to the positioning of the wiper mw5 (II), in the manner explained later, the relay P2 is not energised. As a result earth potential (compare VLI:

earth, WM5, 8lpl) is no t connectedover a p2- contact to the b-conductor of the junction line VLII to the series nal selector, as canv be seen in the case of the junction VLI, whereby a relay operated up till the reply of the required subscriber over the lv-conductor of the iinal selector is restored and on transmission of an engaged signal from the final selector the test conductor c of the junction line of the sub-exchange is disconnected so that this junction line is'released. A further connection to the subscriber already engaged is thus prevented. It can be seen that in the main exchange HA the line of the callingsub-exchange subscriber T112 is marked as being engaged by means of the relay Pl sol that connections over the other line cannot be put through to him. 'j

If, in the meanwhile, the pre-selector VWI started up by the call impulse, has found a free selector, then, in known manner the relay TI is energised whereby the calling subscriber is switched through over the Wipers of the preselector VWI to the numerical impulse' receiver. When the subscriber TnZ operates his dial switch the relays A and B are restored intermittently by interruption of the subscribers loop so thatby the corresponding interruption of the contact 69h a transfer of impulses for setting the subsequent numerical impulse receiver occurs. When the required subscriber has been reached after transmission of the necessary impulse trains, there follows transmission of ringing current. When he replies, the ringing current is disconnected in the known manner and a metering impulse is transmitted over the test conductor by which the winding I of relay Z is operated. By the closing of the contact H52 the meter Z2 corresponding to the calling subscriber T112 and connected to contact 2 over the wiper mw'of the switch in the main exchange, is operated.

When the calling subscriber hangs up at the end of a conversation the relays A and B and, a'short while later, relays A2 and UI are restored by the interruption of the subscribers loop. By the opening of contact 69h the numerical receiver is released as well as Ythe preselector VWI which, over its wiper c, after it has restored to normal, short-circuits the winding II of relay V which after the disconnection of winding I has hitherto remained energised over contact 1Go. 'I'he holding circuit of winding II of relay XI is interrupted by theV opening of contact 5211 so that, during the following return movement, of the selector in the sub-exchange, a testing by a calling subscriber is prevented by means of the relay B (contact 62ml open).r After the release of relay V'and on the opening of contact Illu relay PI is also disconnected. By the closing of contact 53o winding I of relay K is further energised so that now the stepping-on of the sub-exchange selector which is of not further interest, and of the switch in the main exchange to their normal positions, takes place. When the sub-exchange selector has taken its iinal step, as long as the rotary magnet Dwl is still energised, relays MH and MIZ are energised over contact Idwl over the a-conductor of the junction line VLI and resistance Wz'i and over the winding l'of relay XI so that when contact IlmlZ closes after the disconnection of rotary magnet Dwl the permanent current circuit (already indicated) for the multiple connection of the call circuits'is vclos`e ':l. A Y Y As described above the relay B in the main exchange is energised during the existence of a connectionlover the junction line VLI so that at'the junctionline by the opening of contact |046 the short circuit for winding I' of relayv X2 is removed;v As a' result a `further call for setting-up an outgoing connection from the junction line VLII can be undertaken in one of the ways described above in connection with the junction line VLI. The switching arrangecoming connection is set up then the nal selec- 20 tor LWisrst set by means of the characteristic digit of vthe. 'sub-exchange UA. The nal Y selector LWV then tests which line is free in known manner, it then tests, therefore, the next junction line VLII since this is the first line connected in its contact bank. 'If this line is engaged it steps onto thejunction line VLI. When Vthis is Ifree the rlaysZfY 'and TI are Yene'rgisedover the yc-wipe'r of they final selector LW. Over the b-conductor the relay K (winding II) is energised,`from the series nal selector LW. The other-'switching operations (energising of relays Q, V, Xl) `are performed Vafter the rotary magnetDwl has vbeen connected to the b-conductor 'by the interruption of the permanent current circuit over the a-conductor (42g) by the relay K operated by the impulses transmitted over the U-conductor; this switch (44k) in the'main exare performed in the manner when f v connecting the winding IIof relay K (Y restores after the impulse transmission) over the contact Bipl, earth is connectedto the b-conductor of the Vfinal selector so vthat a call is initiated. The required subscriber is connected by the operation of the corresponding A-relay over the wiper wl l after the selector in the sub-exchange has been set in position. At contact 56m relay B is connected to the b-conductor. `When therequiredV subscriber replies the relays A, UI, B operate over the subscribers loop in series with the already energised A-relay of the required subscriber. The disconnection of ringing current in thenal selector is brought vabout by the opening of contact 86h. Further operations are not of interest.

It should be noted that all switching operations describedV for the junction VLI in the setting-up of outgoing or incoming connections using the junction While in Figs.- l and 2 each subscriber is associated'witharelay for each junction line, which according -to the junction line to be used, discon- Y nects him from-the other' junction line, in Fig.

3 each subscriber has two associated relays of which one relay in the anormal position connects him with oneI junction line and inthe operated position with the other junction line while the second relay disconnects the subscriber from the call circuit over the second junction line. Further circuits correspond to those lof Figs. 1 and 2. The main exchange HA can when setting up a connection over the rst junction line be arranged in the same manner in this case.

In the normal position of the system the subscribers are connected to the multipled call circuits of the two junction lines since the relays MIS, MM, M23 and M24 are energised in the permanent current circuit and Atheir contacts take up the positions shown.

If the uper junction line'VMI is free a subscriber T113 can transmit a call impulse to the exchange over the call circuit, multipled for all subscribers in common, and over the upper conductor of the junction VMI in the manner shown in Figs 1 and 2. The selector of this junction, after the disconnection of the permanent current circuit for relays M13 and MM, is

set by the exchange on the calling subscriber..V

Relay B3, energised on the setting -of the selector over its winding I, is maintained energised over the calling subscribers loop in the speaking circuit. By the opening of the rest contact b3, the calling subscriber is disconnected from` the call circuit over the lower junction.

If the upper junction VMI is engaged by a call of the subscriber T113 the relays MIS and MM are restored', and the call impulse of` the subscriber operates, over the upper conductor v of the lower junction line VMII, on` theV associated call arrangements in the main exchange as is shown in Figs. 1 and 2. The selector at this junction is set into operation; when it is positioned on contact 3 relay A3 is energised over its winding I; it connects the calling subscriber T113 over operated contact a3 to the lower Junction line VMII. Over the subscribers loop this relay A3 (winding II) is maintained energised. The subscriber TuS is now disconnected from the call circuit over the upper junction line VMI at a further station.

It can be seen from the above description that on the energising of relay A3 the subscriber is connected to the lower junction while the call circuit extending over the upper junction is disconnected and thaton energising of the relay B3 the calling subscriber remains connected to the upper junction while the call circuit extending over the lower junction is disconnected. In this way the switching technique of the construction of the sub-exchange UAis different in Fig. 3 from the sub-exchange UA of Fig. 1. The selector positioning and testing by the main exchange follows in the manner described with reference to Figs. 1 and 2.

I claim:

1. In a telephone system having main and subexchanges with trunk lines connecting the two,

subscribers lilies in the sub-exchange normally connected to two of said trunk lines; all battery feed for said lines and connections therefrom supplied from the main exchange over said trunk lines, and switching arrangements in said subexchange operated responsive to a call from a exchange over a plurality of said trunk lines, one

of the connected trunk lines being first choice for calls to said lines from the main exchange and the other being first choice for calls to the main exchange, and means in the main exchange for determining which trunk will be used for either type of call.

3. In a. trunking system, a main and a subexchange, a plurality of subscribers lines in the sub-exchange, a plurality of trunk lines connecting said exchanges, each subscribers line connected to a plurality of said trunk lines, a normally closed circuit including one of said trunk lines and a plurality of said subscribers lines, means for controlling said circuit when a call is initiated from one of said subscribers lilies, all battery feed for the sub-exchange supplied solely over said trunk lines, and means in the main exchange for determining the trunk line to be used in extending the call to the main exchange.

4. In a telephone system, a main and a subexchange, subscribers lines in the sub-exchange, a pair of trunk lines connecting said exchanges and supplying all battery feed thereto, a circuit for each trunk line normally including all of the subscribers lines in the sub-exchange, means responsive to the initiation of a call at one of said lines for controlling said common circuits to extend connections to the main exchange over said trunk line, and means in the main exchange for determining the trunk line used.

5. A telephone system such as claimed in claim 4 wherein there is a circuit for each trunk line to each subscribers line and controlled thercat to start the operation of said switches.

6. A telephone system as claimed in claim l wherein one of said trunk lines is always used as first choice for calls to said main exchange and the other as first choice for calls from said main exchange.

7. In a telephone system, a main and a subexchange, a plurality of trunk lines connecting said exchanges, subscribers lines in the sub-ex change, each subscribers line normally connected to all of said trunk lines, means responsive to the initiation of a call from one of said subscribers lines for extending a connection to the main exchange over an idle one of said trunk lines and disconnecting said subscribers line from the other trunk lines, and means in the Inain exchange operated when a call is originated in said main exchange for extending a connection to one of said subscribers lines in the sub-exchange over one of said trunk lines and disconnecting it from the other trunk lines.

8. A telephone system such as claimed in claim 7 wherein all battery feed connections to the subexchange are supplied over said trunk lines from the main exchange.

9. In a telephone system, a main and a subexchange, a pair of trunk lines connecting said exchanges, subscribers lines in the sub-exchange, a normally closed circuit for each trunk line including relays in the branch exchange normally energized, a plurality of branches for each circuit extending to all the subscribers lines, said circuits all controlled by said relays, means controlled by the initiation of a call over one of the subscribers lines fer controlling its branch circuit to complete a connection to the main exchange over one of the trunk lines, and to operate certain of said relays to disconnect the seized trunk line from other subscribers lines.

EUGEN JAUCH. 

